Timothy Davis Sr., 48, is charged with second-degree murder.

The state and defense agree on a lot about what happened at Timothy Davis Sr.'s Apopka home Oct. 1, 2011: During a fight with his son, the retired Orlando policeman retrieved a gun from his car and fired two shots, fatally wounding the younger man.

But in opening arguments Tuesday, prosecutor Jim Altman and defense lawyer Robert Nesmith gave jurors two conflicting motives to chose from: Did Davis Sr. fire out of rage, or out of fear?

Said Nesmith: "This isn't a case of who did it, but, more so, why?"

Davis, 48, is on trial this week in the shooting of 22-year-old Timothy Davis Jr. Charged with second-degree murder, he faces up to life in prison.

"You will hear from the defendant himself, his own confession ... that he killed his son because he lost it," Altman said in his opening. "He lost his cool. He lost his temper. He lost control."

Nesmith argued the elder Davis fired as a last resort: Davis Jr. had injured him in a fight inside the family's home, then followed him outside to continue the beating.

"He's in no position to fight, he can't fight," Nesmith said. "He's been beat up. He's hurt. He's scared."

The state called several civilian witnesses on Tuesday, including Georgina Edmund, Davis Jr.'s ex-girlfriend and the mother of his child. She said she had been trying to get her child from Davis Jr., who didn't want to give up the boy.

When Davis Sr. intervened, Davis Jr. was enraged, she said. Edmund and two neighbors described seeing the father and son shoving each other. The neighbors later heard gunfire.

Several law-enforcement witnesses also testified, including first responders, a firearms expert and a crime-scene investigator.

The CSI testified that investigators found blood in the home's garage and a bullet lodged in a wall. During her testimony, jurors saw Davis' black Kel-Tec gun for the first time.

Davis Sr. was emotional at times Tuesday, and was granted permission to leave court before testimony about his son's autopsy.

Later, jurors heard the police interview Altman called the elder Davis' confession. In the recording, Davis Sr. said he has "always been a man ... If I did something, I fess up to it."

"I just lost it and I'm not proud of it, because I pride myself on being a man and being a cool, level-headed person," Davis says in the recording played for the jury Tuesday.